Vacuum circuit breaker sizing
Vacuum circuit breaker sizing
(OP)
Hello friends
I’m new to MV circuit breaker sizing . Could someone help me size the MV vacuum circuit Breakers A,B, C and D below please
We have a 11kv cable suppling a MV switchgear (A) which is also supplied by a 2mva (B)generator .
The switchgear is supplying two substation with 2.5mva and 3mva transformers(0.4kv/11kv)(C)and (D) respectively - circuit breakers before transformer .
http://files.engineering.com/getfile.aspx?folder=d...
Thank you
I’m new to MV circuit breaker sizing . Could someone help me size the MV vacuum circuit Breakers A,B, C and D below please
We have a 11kv cable suppling a MV switchgear (A) which is also supplied by a 2mva (B)generator .
The switchgear is supplying two substation with 2.5mva and 3mva transformers(0.4kv/11kv)(C)and (D) respectively - circuit breakers before transformer .
http://files.engineering.com/getfile.aspx?folder=d...
Thank you






RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
Could you please show how the size was calculated?
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
It’s just a matter of looking at what’s available and picking one, expressing those load values in Amps is about the only possible calculation in this case.
RE: Vacuum circuit breaker sizing
Actual application rating of Vacuum Circuit Breaker depends on the CT ratio and the relay settings.
Vacuum Circuit Breaker (VCB) is electrically operated switch. There are no overcurrent devices built in. The overcurrent protection and control comes from using current transformer (CT) and protective relays that are mounted in the switchgear assembly. Power is derived from a control source, batteries or control power transformer external to the breaker assembly.
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
1. Protection relay, usually overcurrent relay.
2. Current transformer
3. Power supply, usually a battery bank.
The current transformer senses the current flowing in the circuit breaker. Its secondary output is fed into the overcurrent relay. The overcurrent relay can be set to trip when the current input from the CT secondary reaches a particular level which is commensurate to the overcurrent value at the primary side of the CT. When this condition arises, a trip contact of the relay will energize the trip coil of the medium voltage circuit breaker causing it to trip.
The power supply provides operating power to the overcurrent relay (for electronic relays) and power to trip the circuit breaker when required.
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
Lionel- could you please give me a short introduction about these points and any suggest any good materials or websites to cover them .
Also could you answer my question above and confirm the correct circuit breaker size given the indicated sizes of transformers
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing
RE: Vacuum circuit breaker sizing